Example embodiments of the inventive concepts relate to a three-dimensional (3D) semiconductor device and, more particularly, to a highly integrated 3D semiconductor memory device.
Semiconductor devices have been highly integrated in order to provide excellent performance and low manufacturing costs. The integration density of semiconductor devices directly affects the costs of the semiconductor devices, thereby resulting in a demand of highly integrated semiconductor devices. The integration density of a conventional two-dimensional (2D) or planar semiconductor devices may be mainly determined by the area a unit memory cell occupies. Therefore, the integration density of the conventional 2D semiconductor devices may be greatly affected by a technique of forming fine patterns. However, since, among other factors, extremely high-priced apparatuses are needed to form fine patterns, the integration density of 2D semiconductor devices continues to increase but is still limited. Three-dimensional (3D) semiconductor memory devices have been developed to overcome the above limitations. 3D semiconductor memory devices may include memory cells three-dimensionally arranged.